Summary Estimates from the CDC indicate that over 300,000 people are diagnosed each year with LD. Ecological approaches to decrease B. burgdorferi burden in Ixodes ticks, and transmission to other hosts, are highly desired tools for use instead of the current `check for ticks' approach. It is well established that after a vertebrate host is immunized with B. burgdorferi' OspA they produce antibody that, upon bloodmeal ingestion by a feeding tick, kills B. burgdorferi within that tick. These are known as transmission-blocking vaccines (TBV). These tools, including TBV, have not been proven to decrease B. burgdorferi exposure in critical intermediate incidental host(s). In North America, both humans and dogs are incidental hosts of B. burgdorferi. We and others have demonstrated that dogs can serve as stand-in/proxies for human exposure to infected ticks. Hunting dogs are a robust model for this trial because they serve both as a proxy of an active outdoors incidental host (like people at high-risk of contracting LD) and are a conduit of ticks into domestic habitats, increasing human exposure. The goal of this work is to demonstrate that a commercial-grade reservoir targeted TBV alters B. burgdorferi infection prevalence in questing ticks, in endemic areas (PA and MD) geographically distinct from the first field trial (NY). To show proof-of-principle for an ecological disruption of Borrelia transmission, we propose to: 1) establish the efficacy of a commercial-grade reservoir targeted transmission blocking vaccine (TBV) in reducing prevalence of B. burgdorferi in the tick vector and how it affects clinical disease in incidental hosts (dogs) in a five-year field study 2) Use a Bayesian hierarchical statistical model to estimate how TBV treatment of infected ecosystems will alter human B. burgdorferi exposure. These proposed studies are highly significant to public health as a field trial demonstration of a TBV that disrupts the enzootic transmission cycle of B. burgdorferi to incidental hosts. Furthermore, demonstration of reduced human (incidental host) Lyme disease will be performed through a stochastic Bayesian model that will provide critical evidence for a new tool to decrease environmental exposure to Lyme disease. This work innovates as a demonstration of an efficacious, easily distributable and inexpensive TBV that reduces B. burgdorferi prevalence in nymphal and adult ticks, as well as B. burgdorferi transmission from ticks to incidental hosts. Reduction of transmission of B. burgdorferi to incidental hosts as a result of TBV distribution will prove to be a paradigm-shifting strategy to reduce the burden of Lyme disease in veterinary and human populations. Findings from experiments proposed in this study will advance translational knowledge of B. burgdorferi vaccinology and will provide strong evidence regarding the possibility of TBV reducing the human health risk of exposure to Lyme disease across the United States.